for more information on kanvasbuddy see https://github.com/Kapyia/KanvasBuddy
KanvasBuddy is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or any later version.
KanvasBuddy is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should receive a copy of the GNU General Public License along with KanvasBuddy. If not, see https://www.gnu.org/licenses/.
Long story short: you're free to download, modify as well as redistribute KB as long as this ability is preserved and you give contributors proper credit. This is the same license under which Krita is released, ensuring compatibility between the two.